Green Energy Innovations
Renewable energy technologies are advancing rapidly with discoveries in material science and engineering. Despite these advances, the use of linear actuators may provide the renewable energy industry with an added boost in innovation, allowing for higher electrical efficiencies and an attractive return on investment. It is essential to touch on some technology-specific advances in solar photovoltaic (PV) and wind energy to understand how linear actuators could promote this innovation in the renewable energy space.
The progression of renewable energy and its advancements has been significant in modern times, with new technologies, studies, and methods arising through extensive research and new devices. Linear actuators are one such device that has arisen to automate and improve the renewable, ‘green’, energy industry. We will first give an overview of the advancements in solar photovoltaics and wind energy industries before delving into the precise role linear actuators play.
Solar Photovoltaics: An Overview
Solar photovoltaics involves capturing the sun’s energy (i.e. photons) and converting the chemical reaction that takes place within a solar panel, into electrical energy. In 1960, the first commercially available solar cell only reached an efficiency of approximately 10%. However, advances in solar PV technology has seen this efficiency increase while simultaneously lowering the cost per kilowatt.
The highest recorded efficiency to date for a solar panel is 22.8% (SunPower panels). The low-cost of solar PV technology has caused a rapid uptake of the technology in many countries, but extensive studies are now being done to focus more on improving efficiency instead of the cost, which will eventually level out. On that note, historically, the chemical reaction within a solar cell involves a photon of light knocking out a single electron, which limits the theoretical electrical output of the cell. Yet, MIT and Princeton University graduates have recently pushed past this theoretical limit and can demonstrate knocking out two electrons with a single photon. This innovation could drastically improve the overall efficiency of silicon-based solar cells.
Solar Panel Actuators
The Renweable Energy (RE) industry has benefited significantly from the advancements in technology/science, and linear actuators in green energy have played a major role in these advancements. However, linear actuators could provide solar technologies (PV and concentrated) with a further leading edge to promote the uptake of green energy solutions.
Electric linear actuators are commonly used for solar panel tracking, whereby the actuator tilts the panel to face the sun so that direct sunlight hits the panel at close to perpendicular to its surface. Solar panel tracking allows for sustained photon energy to hit the panel for a longer operating time compared with fixed solar panels.
Solar tracking using a linear actuator has several benefits. Firstly, linear actuators provide a smoother operation through its stroke compared with using more expensive stepper motors. Secondly, quality electric linear actuators can also operate in harsh conditions and are designed to be rugged, durable, and easy to install – making them ideal for large-scale projects that are located on vast landscapes. Lastly, the efficiency of linear actuator solar panel tracking can increase conversion efficiencies by 25% to 40%.
Linear actuators can also be used to tilt the mirrors of a concentrated solar plant, providing accurate positioning of the reflected sunlight on to the central tower. The actuators are environmentally friendly as they do not leak fluids as seen with hydraulic actuators. They require little to no maintenance and have low power consumption.
Wind Energy: An Overview
Wind energy is generated by using a wind turbine, which converts rotational energy, from the moving turbine blades, into electrical energy. Wind turbines come in an array of forms such as vertical or horizontal-axis turbines, with the number of blades used optionally. The most used wind turbines are the horizontal-axis turbines as they have higher efficiency compared with vertical-axis turbines. These horizontal-axis turbines can reach a power rating of three megawatts with a rotor diameter of 100 meters (Acciona AW model), but the size of a wind turbine is a limiting factor. The material used for the hub and rotor blades can only withstand so much force before failing. By using newly discovered, re-enforced materials, the largest wind turbine created was able to produce 12 megawatts of electricity with a rotor diameter of 220 meters (Haliade-X model). If material science innovations continue at its current pace, future wind turbines are expected to produce 20 megawatts with a rotor diameter of 250 meters (see below graphic for a timeline in wind turbine progression).
Wind Turbine Progression
Other wind energy technology advances include the improved efficiency of the rotor drivetrains by reducing the wear and tear on moving parts. Also, the Internet of Things (IoT) sensors and artificial intelligence are being used to schedule future wind turbine maintenance to avoid inevitable turbine failures.
Linear Actuators for Wind Turbines
Linear actuators in wind turbines serve a slightly different purpose than with their use in solar technology. Wind turbines cannot operate when the wind is too strong as it would cause the blades to snap from the turbines rotational speed being exceeded. Therefore, the blades of the turbine are rotated and locked in place with a linear actuator. The rotated configuration of the blades allows the wind to flow past without causing a downward force on them, preventing the blades from spinning. Additional linear actuators are usually also used to lock the rotor and Nacelles in place.
Besides the use of linear actuators on the direct operation of a wind turbine, they also provide an ergonomic solution by opening/closing service hatches or access gates. Wind turbine maintenance workers would require considerable strength to open these heavy hatches without the use of a linear actuator. Control systems attached to the linear actuator network also allow for the operation of the wind turbine to be controlled from a central station.
Future Green Energy Innovations
Besides traditional solar PV and wind energy technology, other innovative technologies, such as ocean energy, are undergoing proof-of-concept phases to determine their viability. The most popular ocean energy technology uses an electric linear actuator attached to the seabed and is connected via a cable to a bouy. As the bouy moves up and down, it pulls the linear actuator and uses that motion to generate electricity, essentially reversing the operation of a standard actuator.
Also, new, thin-film solar cells are emerging in the market (e.g. dye-sensitised, organic, and quantum dot solar cells), which would allow for these technologies to be integrated into building windows due to their flexibility, transparency and low-cost of manufacturing. Electric linear actuators have already been used to improve this technology, shifting the panels on a building to provide adequate exposure to the sun throughout the day.
Moreover, concentrated solar power is becoming a popular alternative to traditional solar PV in the northern region of South Africa, where solar radiation is adequate for large power plants. Concentrated solar power reflects sunlight towards a central tower, which heats a chamber filled with a particular substance that can retain the heat. The thermal energy is then converted into electrical energy when needed.
Extensive research and innovation have led to the development of new methods for storing the thermal energy for extended periods, thereby allowing for electricity to be generated at nighttime. Electric linear actuators are a very popular choice for these projects as the location of these plants are generally in very hot regions, which a linear actuator would have no problem handling due to their robust design.
The RE industry will continue to grow as the need for reducing the effects of carbon emissions on the planet increases. Electric linear actuators promote innovation, with their uses are endless across all areas. Furthermore, the benefits of linear actuators outweigh the pros of using servo motors for actuation. The use of servo motors in renewable energy technology have their place, but they tend to be more expensive and require additional gearing to slow down significantly.
On the other hand, electric linear actuators are cheaper, more robust, easy to install, and their speed settings are easy to adjust without an added gearbox. Despite RE innovations already moving rapidly, linear actuators would allow for that extra investor push to reach a maximum return on investment, guaranteeing a speedier, more efficient green project with a higher level of confidence.